Surface de contamination of seeds to produce axenic seedlings

Surface de contamination of seeds to produce axenic seedlings

Sweet H.C.; Bolton W.E.

American Journal of Botany 66(6): 692-698

1979

A variety of sterilizing agents were tested to develop a standard procedure for surface decontaminating seeds [cabbage, corn, lettuce, pine, radish, rice, spinach, sorghum, soybean, sunflower, tomato and wheat] to produce axenic seedlings. The use of calcium hypochlorite (0.5% phosphate buffer, pH 6) for 10 min followed by 3 sterile water rinses was among the most effective agents and it did not injure some species as did sodium hypochlorite, formaldehyde, ethylene oxide and mercuric chloride. Some species contained internal microbes requiring severe treatments which killed or injured the seedling; other species were decontaminated with a sterile water rinse. The percentage of seeds with internal microbes varied considerably among plant species, seed lot and the length of seed storage. Thus, with seeds not easily decontaminated, screening of additional seed lots would be more profitable than testing additional decontamination agents. Release of microbes from the seed's interior is associated with germination and microbial testing must last at least 11 days. Nutrient agar permitted growth, although the seedlings outgrew petri plates to quickly for adequate certification. These seedlings were transferred to nutrient agar in quart jars in which an internal pool of broth was periodically agitated to permit microbial sampling of the leaves while the plant grew.